OFDM Subcarrier Phase Rotation Without Mixing Frequency Alignment
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Solution Overview
Problem
Existing OFDM systems require mixing frequency alignment between transmitting and receiving ends, leading to increased signaling overheads and system complexity.
Innovation Solution
Perform phase rotation based on a reference frequency at the transmitting end without knowing the receiving end's mixing frequency, and perform phase reverse rotation at the receiving end based on the same reference frequency, eliminating the need for mixing frequency alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mixing frequency alignment is performed between transmitting and receiving ends, then modulation and demodulation can be correctly implemented, but signaling overheads increase and system complexity increases
Solution Approach 1:
The patent extracts the frequency alignment requirement from the system by using phase rotation that is independent of mixing frequency. The transmitting end applies phase rotation based only on its own reference frequency, and the receiving end applies reverse phase rotation based on its own reference frequency, eliminating the need for mixing frequency alignment between ends.
Solution Approach 2:
The patent changes the parameter used for phase rotation from mixing frequency (which requires alignment) to reference frequency (which does not require alignment). By using local reference frequencies at each end, the system achieves correct modulation and demodulation without needing to negotiate or align frequency parameters between transmitting and receiving ends.
2Reliability
If mixing frequency alignment is performed between transmitting and receiving ends, then modulation and demodulation can be correctly implemented, but signaling overheads increase
Solution Approach 1:
The patent removes the signaling overhead associated with mixing frequency notification by making phase rotation independent of mixing frequency. Each end uses its own reference frequency for phase rotation, so no information about the peer end's mixing frequency needs to be transmitted or negotiated.
Solution Approach 2:
Each communication end independently performs phase rotation using its own reference frequency without needing information from the other end. The transmitting end self-determines the phase rotation based on its reference frequency, and the receiving end self-determines the reverse phase rotation based on its reference frequency, eliminating the need for frequency alignment signaling.
Data Source
AI summary
A method includes: determining a plurality of first subcarrier data items on a plurality of first subcarriers of a first frequency subband; performing first phase rotation on each first subcarrier data item based on a mixing frequency and a first reference frequency corresponding to the first frequency subband; determining a to-be-transmitted signal based on a plurality of first subcarrier data items obtained through first phase rotation; and sending the to-be-transmitted signal. In this way, phase rotation can be performed based on at least the first reference frequency, so that modulation can be correctly implemented without a need to know a mixing frequency of a receiving end. In addition, there is no need to notify the receiving end of the used mixing frequency, and the receiving end can correctly demodulate a received signal even if the receiving end does not know the mixing frequency.